ABSTRACT
Background The measurement of corneal Q value is essential for corneal refractive surgery and calculation of intraocular lens during cataract surgery.Topolyzer was often used for the measurement of Q value,and recently Topcon KR-1W and iTrace were applied in ophthalmology.However,whether the measured values are interchangeable is unclear.Objective This study was to assess the difference and consistency of corneal Q values measured by Topcon KR-1W,iTrace and Topolyzer.Methods Corneal Q values were measured on 100 right eyes of 100 healthy subjects under the approval of Ethic Committee of the Sixth Hospital Affiliated to Shanghai Jiaotong University and informed consent of each subject from November to December in 2014 with Topcon KR-1W,iTrace and Topolyzer.Three valid measurements were obtained for each device,and the average values from each device were calculated.The difference of the outcomes among the instruments was compared by repeated measures analysis of variance (ANOVA),and the consistency among the outcomes from different apparatus was analyzed by Bland-Altman plots.Results The mean corneal Q values were-0.184-±0.112,-0.117±0.167 and-0.269±0.117 from Topcon KR-1W,iTrace and Topolyzer,respectively,with a significant difference among them (P ＜ 0.001).The measured Q value by Topcon KR-1W was 0.085±0.010 larger than that by Topolyzer,and the Q values by iTrace was 0.152± 0.014 larger than that by Topolyzer,while the Q values obtained by Topcon KR-1W was 0.067±0.016 smaller than that by iTrace (all at P＜0.05).The 95％ confidence interval of the values between Topcon KR-1W and iTrace,Topcon KR-1W and Topolyzer,iTrace and Topolyzer were-0.106 to-0.028,0.060 to 0.109 and 0.118 to 0.186,respectively.Bland-Altman plots showed that 6％,6％ and 5％ values were outside of 95％ agreement of limit (LoA) between Topcon KR-1W and iTrace,iTrace and Topolyzer or KR-1W and Topolyzer,respectively,with the maximal differences of 0.28,0.43 and 0.38.Conclusions Corneal Q values measured by Topcon KR-1W and iTrace are larger than those measured by Topolyzer.Due to the poor agreements among the corneal Q values by the 3 kinds of devices,they are not interchangeable in clinical applications for the measurement of corneal Q value.
ABSTRACT
·AlM: To investigate the distribution and related factors of corneal spherical aberration in the age-related cataract patients, and to provide a scientific basis for the application of aspheric intraocular lens ( lOL ) in cataract surgery patients. · METHODS: Retrospective study of 509 age -related cataract patients of 610 eyes in our hospital. Corneal spherical aberration, corneal curvature, corneal astigmatism and corneal Q -value were examined by iTrace visual function analysis. Statistical software SPSS16.0 was used to analyze statistically. · RESULTS: The range of corneal spherical aberration was 0 ~1.800μm. The mean coefficient of corneal spherical aberration was 0.266 ±0.010μm. Corneal spherical aberration was no significantly correlation with age, corneal curvature, corneal astigmatism ( r =0.71, 0.56, 0.93, P>0.05 ). There was positive correlation between corneal spherical aberration and Q-value ( r=0.086, P=0.03). · CONCLUSlON: Corneal spherical aberration varied greatly among age-related cataract patients.The choice of asphericity intraocular lens should be a matter of personal choice.
ABSTRACT
Background Aspheric intraocular lens (IOL) is designed to reduce the spherical aberration of the eye after cataract surgery and to obtain better visual quality.However,the selection of a personalized aspheric IOL is a problem to be solved.Objective This study was to compare the wavefront aberration and quality of vision of patients between the implantation of negative spherical aberration IOL and non-aberration IOL,and to investigate the relationship between corneal Q values and postoperative spherical aberration.Methods One hundred and four eyes of 90 patients with age-related cataract were randomized into two groups.Fifty-two eyes of 46 patients who received a Tecnis Z9001 IOL implantation were assigned as the negative spherical aberration IOL group and 52 eyes of 44 patients who received Akreos AO IOL without aberration were assigned as the non-aberration IOL group.The preoperative corneal Q values were measured and the mean Q value(Q)was computed.Then the patients in the two groups were further divided into 2 subgroups,respectively,based on their Q values were over or below (Q）.The corneal Q values,root mean square(RMS) of ocular spherical aberration,coma and total higher-order aberrations(HOAs) for 5 mm diameter pupil,scotopic contrast sensitivity with or without glare at 6 mm pupil diameter were measured 3 months after surgery.Results The pre-and post-operative corneal Q values were insignificantly changed (t =1.447,P =0.151).The spherical aberration in the negative spherical aberration IOL group was(0.059-±0.047)μm,and that in the non-aberration IOL group was(0.110±0.066)μm,with a statistically significant difference between them (t =-4.567,P=0.000).Scotopic contrast sensitivities at intermediate and high frequencies were significantly better in the negative spherical aberration IOL group than in the non-aberration IOL group (t =2.495,t =2.359,P ＜ 0.05).There was no significant difference in coma and HOAs between the two groups after operation (P ＞ 0.05).Weak positive correlations were seen between the pre-and post-operative corneal Q values and spherical aberration in the two groups(r=0.277,0.292,0.285,0.325,all at P＜0.05).However,no significant differences were found in spherical aberration,contrast sensitivity and scotopic contrast sensitivity between the different subgroups (P ＞ 0.05).Conclusions Negative spherical aberration IOL has lower spherical aberration and better scotopic contrast sensitivity than non-aberration IOL.The results suggest that it may be not enough to choose the corneal Q value only as the single reference criterion for selection of aspheric IOL.